Hi Rizla,
S06s and E17z usually send each message for two weeks in a row and at the end of the month.
Example: new msg on 1 June, repeated on the 8th, new on the 15th, repeated on the 22nd and a null msg on the 29th.
The messages are repeated from time to time, as a whole or as part of a longer message. Have a look at this one: 427 806 5 46062 68672 97478 39685 30485 806 5 00000
The string 46062 68672 97478 39685 30485 has also been sent on 13-12 2011, 09-04-2013, 13-10-2013, 02-01-2015, 09-01-2015, 15-08-2017, 22-08-2017
Cheers
Ary